Process for the preparation in an acid medium of chromed dyestuffs and products resulting from this process



Patented Oct. 18, 1938 ENT OFFICE 7 PROCESS FOR THE PREPARATiON IN a ACID MEDIUM or CHROMED DYESTUFFS SULTING FROM THIS AND PRODUCTS RE PROCESS Georges Kopp, Rouen, France. assignor to C'oml pagnie Nationale de Matieres Colorantes et Manufactures de Produits Chimiques du Nord Reunies Etablissements Kuhlmann, Paris, France, a corporation of .i.

France No Drawing. Application November 12, 1934,serial No. 752,788. In France December 2; 1933 3 Claims. (01160 -447) In U. S. Patent 'No. 1,921,586 is described-a process for the preparation of chromed complexes of ortho-hydroxy-azo dyestuifs consisting in treating these dyestuffs with salts of chromium 5 with a mineral acid radicle without efiecting the neutralization customarily recommended of themineral acid liberated in the course of the fixation of the chromium on the coloring material. It has been indicated in addition that this treatment can be efiected in the presence of a free mineral acid added to the bodies taking part in the reaction and more particularly in the presence of sulphuric acid. This process permits of obtaining chromed dyestuffs of which the shade andthe properties are considerably dilferent from those of the chromed dyestuffs obtained by the customary methods in the absence of mineral acid. Actually it has been found that the forma tion of these new chromed compounds takes place in two principal phases.

In the first place the ortho-hydroxy-azo dyestufis form, with the oxide of chromium yielded by the chromium salts, chromed compounds which are very soluble in water, characterized by an excellent affinity for the animal fibre but in general having the disadvantage of being too sensitive to the action of acids. The dyeings obtained by means of these products are generally strong, of flat shades and often uneven. These 3.0. products which are obtained most easily in a neutral or very slightly acid medium are precisely those to which are directed the processes in which a neutralization is effected of the liberated acid. They will be designated in the present application by the expression primary chromed compounds.

In the second place under the prolonged action of the chroming media rendered strongly acid by the presence of the mineral acid derived from the chromium salts and if desired by the previous addition of acid, these primary compounds are converted into other chromed compounds char: acterized chiefly by their great resistance to acid agents ofall types. Compared with the primary products which correspond thereto the new dyestuffs present the advantage of giving brighter and more even shades. In addition they are generally more resistant to the action of light. They contain in general the same number of atomsof 5,0 chromium per molecule. These compounds will be designated in the present application by the expression secondary chromed compounds.

An analogous conversion of primary chromed compounds into secondary chromed compounds lsobtained by the process whichwas the object.

of U. S. Patent No.'-1,924,6 96 and which consists in heating in the presence of dilute sulphuric acid the chromed complexes of certain Ortho-- hyroxy-azodyestuffs. By this process the trans;

formation is carriedout, as by the process of the 5;:

Patent No. 1,921,586, in a mineral acid medium, but the phase of transformation is quite distinct from the. phase of formation of the primary chromed compounds, the latter being previously obtained by any known processes. In addition the .Patent No. 1,924,696 only contemplates the application of the process to a relatively limited class .ofchromed complexes of ortho-hydroxyazo dyestuffs, those derived from the dyestuffs obtained by the coupling of ortho-aminophenols or ortho aminonaphthols and their substitution products with pyrazolones.- .1

Now it has been found in accordance with the present invention that in a general manner'it is possible -to cause the conversion of primary chromed compounds into secondary chromed compounds by subjecting the former to a treatment in an acid medium, the acidity being obtained either by the addition of any suitablemineral, organic or sulpho-aromatic acids or by salts of acid character or compounds capable of providing acid compounds. or also by mixtures comprising'several of these products and that in addition this treatment is applicable to all the ortho-hydroxy-azo dyestuffs. 7

. .The conversion process can likewise be elfected in a veryvaried manner. In particular the conversion can be effected in the presence of products taking no partin' the spe'cificreaction of the acids. 7

It is for example possible to apply the process of the inventionv without separating the orthohydroxy-azo dyestufis from their coupling media or media from the first phase of chroming.- It is also possible to apply the conversion treatment in an acid medium to primary chromed compounds obtained by the customary processes and isolated: from their media of formation. 7

This treatment can be effected under all conditions of temperature, volume or pressure and if desired in the presence of organic solvents. However it has been found thatthe conversion takes: place particularly well in the absence of electrolytes, that is, materials capable of evolving acid ionsandbasic ions under'the action of an electric current; this absence-permits chiefly the lowering of the temperatures of the reactions and the shortening of their duration; V y

In certain cases the general process according to the invention permitsofefiecting an economy the azo dyestuff mentioned in Patent No. 1,924,696 and containing molecule of Cr(OI-l) 3 per molecule of dyestufi, is converted in accordance with Example 7 of the present application into a new chromed compound which is a well defined crystalline substance dyeing wool a bright rose color. This compound likewise contains molecule of Cr(OH)3 per molecule of dyestuff. However, it exhibits the same very advantageous tinctorial properties as the dyestufi obtained by heating under pressure for 24 hours of the same starting azo dyestufi in the presence of a solution of chromium sulphate according to Example 1 of- Patent No. 1,921,586 and which contains 1 molecule of Cr(OH)3 per molecule of dyestuif.

It has further been found that the process of the invention can be applied advantageously t0 the mixture of dyestufis containing metals, thus giving rise to the formation of new homogeneous products which it would be impossible to prepare by mixing chromed compounds obtained separately (for example according to the process of either one of the patents above referred to) the inferiority of such mixtures being shown particularly when the constituents exhibit in addition to differences of shades very different physical or chemical properties. If for example a very soluble dyestuff is mixed with a difficultly soluble dyestuif it is difficult to obtain level shades; it is the same when the constituents of the mixture have for the textile fibres unequal aflinities. These disadvantages are eliminated for the products obtained in accordance with the new process, the individual properties of the constituents having disappeared.

The new process can likewise be applied in such amanner as to obtain not only the pure secondary compounds but also mixtures of primary or secondary compounds.

The following examples illustrate the present invention without limiting the same thereto.

Example 1 There are heated under reflux for several hours 30 parts of the azo dyestufi obtained by the coupling of the diazo derivative of l-hydroxybenzene-2-amino-4-sulphonic acid and l-phenyl- 3-methyl-5-pyrazolonewith parts of chrome alum, 15 parts of crystallized sodium acetate and 600 parts of water. After several hours heating the whole has passed into solution. The chromed compound thus formed dyes wool from an acid bath in orange red shades. It exhibits the disadvantage of being very uneven and of being converted by 'dilute acids into an orange yellow product.

0n continuing the heating the crystallization is found to take place of a dyestufi whichis very difficultly soluble in water. After 24 hours heating the whole is precipitated and the primary reddish compound is found to have completely disappeared. The secondary compound dyes wool in orange yellow shades which are more even and more resistant to light than the primary compound- The dyestufi thus obtained is identical with that which is formed when the primary compound isolated by salting out is treated with an acid compound for example under the conditions of Patent No. 1,924,696.

' The secondary compound is obtained as free :acid practically insoluble in water and in most organic solvents. It can be employed in the form of pigments fast to light.

Converted into soluble salt, for example into the sodium salt, it can be employed for the dyeing of natural or artificial textile fibres in an alkaline, neutral, or acid bath. Its solubility in organic solvents permits of its use in the coloring of varnishes and plastic masses.

Example 2 There are heated in an autoclave parts of the azo dyestufi obtained by coupling the diazocompound of 1-amino-naphthalene-2-hydroxy- 4-sulphonicacid'and B-naphthol with 10 parts of common salt, 10 parts-of chromium formate containing of C1203, 15 parts of crystallized sodium acetate and-500 parts of water. After 2 hours heating at C. the whole has passed into solution and non-chromed dyestuif can no longer be detected. I

The product obtained dyes wool in aneutral or acid bath a dull greyblue. This product is decomposed under the action of acids on the one hand into non-chromed dyestufi and on the other hand into a new chromed compound diificultly soluble in water. 7

In order to obtain only the secondary chromed compound there are added to the primarycompound obtained in accordance with the first paragraphof this example 10 parts of hydrochloric acid of 30% HCl and the heating is continued for 6 hours to 105 C. i It is thenfound that the new chromed compound has been almost completely precipitated. It is'soluble in alkalies with the formation of salts which can be isolated by salting out and filtration. The products thus obtained dye animal fibres in a neutral or acid bath in a pure fast blue.

The secondary compound is distinguished from the primary compound likewise by the following reactions. 3

The aqueous solutions of the sodium salts exhibit very different changes of color in contact with the followingchemical agents:

HO] 10 Be. NaOH 5% V 10% Primary compound Grey "Black red .7. Blue black Secondary com- Bright blue green. Bright vio- Violet red. pound. 3 let.

The-colorations of the solutions in pure concentrated sulphuric acidare as follows:

rimary compound: bright indigo blue.

Secondary compound: fiat blue green;

Example 3 30 parts of the azodyestuff obtained by the coupling of the nitro-diazo derivative of l-aminonaphthalene-2-oxy-4-sulphonic acid and 8- naphthol are heated to .C. with 500 parts of water, 50 parts of "a solution of chromium naphthalene-1.5-disulphonate containing 5% of.

original reddish black shade to change to greenish black.

Instead of isolating the primary chromed compound 10 parts of formic acid can be added and heating continued for a further two hours at G. Then the formation of the secondary chromed compound is found to take place which separates in the crystalline form. Salt is added to complete the precipitation and the product is filtered and dried.

The dyestuff obtained is very different from that obtained in the first place. It constitutes a mixture of the primary and secondary chromed compounds; the formation of the latter is due to the action of the formic acid.

If the heating in the presence of formic acid is prolonged the secondary compound is obtained in the pure state.

The secondary compound is converted into soluble salt. It dyes wool greenish black very even shades.

The mixtures of the primary and secondary compounds give blacks which are very interesting on account of their shades and their fastness properties. They likewise permit dyeing in pure fast grey shades.

When the mixtures are rich in secondary compound it is of advantage to render them soluble by salt formation.

Example 4 To the products employed in the example of Patent No. 1,924,696 (that is to say the red blue chromed complex obtained in the absence of mineral acid starting from 42.5 kg. of the azo dyestuif prepared by the action of the diazo compound of 1-amino 2-oxynaphthalenel-sulphonic acid on 1-phenyl-3-methyl-5-pyrazolone and to which are added 400 litres of water with the addition of 8 kgs. of sulphuric acid of 66 B.) are added 5 kgs. of the primary chromed compound of the azo dyestuff obtained by coupling the diazo derivative of 1-aminobenzene-Z-oxy-4-sulphonic acid with fi-naphthol. Then the whole is heated in a lead-lined autoclave under pressure to C. for 20 hours according to the directions of Patent No. 1,924,696.

A bluish red is obtained which is very soluble and in which it is not possible to detect the two components. The dyestufi dyes animal fibre a Bordeaux shade which is very even.

The two compounds prepared separately and subsequently mixed do not permit of obtaining the same effect; the evenness is defective.

Example 5 20 parts of the primary dyestulf of Example 1 above are intimately mixed with 100 parts of Water and 1 part of 96% sulphuric acid; the paste obtained is dried in a vacuum at 100 C. By this treatment a partial transformation is effected of the primary chromed compound into the secondary chromed compound. After solubilization, for example by conversion into the sodium salt, the dyestuff obtained dyes animal fibre in a neutral or acid bath a pure orange of very good fastness.

Example 6 20 parts of the pure primary chromed compound obtained by salting out and filtration of the first reaction product of Example 3 above are heated during 4 hours to 105 C. with 300 parts of water and 5 parts of hydrochloric acid' containing 30% KC]. A dyestuif is obtained which is insoluble in the state of free acid but which after conversion into the ammonium salt can be employed for the dyeing of animal fibres in fast grey shades. This product exhibits physical, chemical and tinctorial properties which are very different from those of the primary product but it has the same molecular concentration-of chromium oxide.

Example 7 25 parts are prepared of the primary chromed compound of the azo dyestufi resulting from the combination of -diazo-2-naphthol-4-sulphonic acid with 1-phenyl3-methyl-5-pyrazolone; the primary chromed compound is obtained in accordance with the customary process for example by means of chromium sulphate and sodium acetate. This chromed dyestuff which is very soluble in water dyes wool a dull bluish red shade; it has the disadvantage of being uneven and of giving irregular shades on account of its sensitivity to the acids of the dye baths.

This compound is converted into the secondary compound by heating in an autoclave for 5 hours to C. with 400 parts of water and 11 parts of benzene-sulphonic acid. The new chromed compound crystallizes in the form of bronze prisms practically insoluble in water. It exhibits the tinctorial properties of the dyestufi obtained according to Example 1 of Patent No. 1,921,586. However it only contians molecule of Cr(OH)3 while the dyestuif of Patent No. 1,921,586 contains 1 molecule per molecule of dyestuff.

I claim:

1. Process for the manufacture of a chromiferous azo dyestuff which dyes pink tints, consisting in heating with benzene sulfonic acid the chromium compound that dyes blue-red tints and is obtainable by the usual chroming methods from the azo dyestuff of the formula 2. Process for the preparation of chromed dyestuffs consisting in heating in an acid medium mixtures of azo dyestuffs each containing a metal, said dyestuffs being ortho-hydroxy-azo dyestuffs.

3. Chromed dyestuffs obtained by heating in an acid medium mixtures of azo dyestuffs each containing a metal, said dyestuffs being orthohydroxy-azo dyestuffs.

GEORGES KOPP. 

